Silvestre Oltra

Rapid Screening of ASXL1, IDH1, IDH2, and c-CBL Mutations in de Novo Acute Myeloid Leukemia by High-Resolution Melting

Recently, many novel molecular abnormalities were found to be distinctly associated with acute myeloid leukemia (AML). However, their clinical relevance and prognostic implications are not well established. We developed a new combination of high-resolution melting assays on a LightCycler 480 and direct sequencing to detect somatic mutations of ASXL1 (exon 12), IDH1 (exon 4), IDH2 (exon 4), and c-CBL (exons 8 and 9) genes to know their incidence and prognostic effect in a cohort of 175 patients with de novo AML: 16 patients (9%) carried ASXL1 mutations, 16 patients had IDH variations (3% with IDH1(R132) and 6% with IDH2(R140)), and none had c-CBL mutations. Patients with ASXL1 mutations did not harbor IDH1, [corrected] or CEBPA mutations, and a combination of ASXL1 and IDH2 mutations was found only in one patient. In addition, we did not find IDH1 and FLT3 or CEBPA mutations concurrently or IDH2 with CEBPA. IDH1 and IDH2 mutations were mutually exclusive. Alternatively, NPM1 mutations were concurrently found with ASXL1, IDH1, or IDH2 with a variable incidence. Mutations were not significantly correlated with any of the clinical and biological features studied. High-resolution melting is a reliable, rapid, and efficient screening technique for mutation detection in AML. The incidence for the studied genes was in the range of those previously reported. We were unable to find an effect on the outcome.

Aberrant methylation of tumor suppressor genes in patients with refractory anemia with ring sideroblasts

This study evaluates the incidence and prognostic impact of aberrant methylation of 25 tumor suppressor genes in 40 patients with RARS, a MDS subtype, by methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) assay. Methylation of at least one gene was detected in 18 patients (45%). The genes methylated were CDKN2B (20%), RASSF1 (18%), RARB (10%), CDH13 (7.5%) and FHIT (5%). Patients with at least one methylated gene had a significantly shorter OS than patients without methylated genes. Aberrant methylation is a frequent event in patients with RARS as in patients with high-risk MDS appears to confer a worse prognosis.

WT1 isoform expression pattern in acute myeloid leukemia

WT1 plays a dual role in leukemia development, probably due to an imbalance in the expression of the 4 main WT1 isoforms. We quantify their expression and evaluate them in a series of AML patients. Our data showed a predominant expression of isoform D in AML, although in a lower quantity than in normal CD34+ cells. We found a positive correlation between the total WT1 expression and A, B and C isoforms. The overexpression of WT1 in AML might be due to a relative increase in A, B and C isoforms, together with a relative decrease in isoform D expression.

Negative impact on clinical outcome of the mutational co-occurrence of SF3B1 and DNMT3A in refractory anemia with ring sideroblasts (RARS)

Abstract The incidence of SF3B1 mutations in patients with RARS is high. Recently, it has been shown that SF3B1 and DNMT3A mutations overlap more often than expected, although it is not clear how this could affect the disease. We studied SF3B1 and DNMT3A in 123 RARS patients: 101 out of 123 samples (82%) had somatic mutations in SF3B1, and 13 of them (13%) showed a co-mutation (SF3B1mutDNMT3Amut). All co-mutated patients had a normal karyotype, and 12 of them (92%) were lower-risk patients (IPSS and IPSS-R). Despite their favorable profile, SF3B1mutDNMT3Amut patients showed a higher RBC transfusion dependency (92% versus 48%, p = .007), a shorter overall survival (OS) (median, 30 versus 97 months, p = .034), and a higher risk of progression to acute myeloid leukemia (AML) at 5 years (25% versus 2%, p = .023) than SF3B1mutDNMT3Awt patients. In conclusion, DNMT3A mutations are present in a significant proportion of SF3B1mut patients with a negative clinical impact.